One of the hottest growth stories just got hotter.

Research In Motion (NASDAQ:RIMM) shares are up 15% to $69.43 this afternoon after the handheld device maker posted another strong quarter of results and continued to bump already-explosive sales and earnings forecasts even higher. For the first quarter, revenues jumped 28% from the fourth quarter and 158% from last year's quarter to $269.6 million, helping turn last year's loss into a $0.28 per-share profit. Meanwhile, the company added 270,000 BlackBerry subscribers during the quarter, finishing the quarter with about 1,340,000 subscribers.

But it's the even brighter future that has the market in a frenzy.

Research In Motion bumped its second-quarter revenue forecast up $20 million to between $290 million and $310 million while raising its earnings expectation to $0.32 to $0.37 per share from its previous guidance of $0.24 to $0.29. That momentum is expected to accelerate in the third quarter, with the company earning $0.35 to $0.40 per share on sales of $340 million to $360 million.

As Chairman Jim Balsillie said in the earnings release, the company's "carrier partners are experiencing significant success in the market place and are further expanding sales and marketing efforts to capitalize on the growing interest in BlackBerry."

So Research In Motion's intriguing growth story continues. A big part of that is success in pushing the "CrackBerry" into international markets, helped by a growing list of business partners and clients such as PalmSource (NASDAQ:PSRC), Nokia (NYSE:NOK), IBM (NYSE:IBM), Motorola (NYSE:MOT), and Vodafone (NYSE:VOD). The stock's performance has reflected this, providing an almost neat seven-bagger over the past year.

The real question now is valuation, which -- given Research In Motion's explosive growth success -- doesn't even look all that scary. For more on this growth story, interested investors should check out:

How far can BlackBerry go? Share your thoughts on the Research In Motion discussion board.

Fool contributor Jeff Hwang owns none of the companies mentioned above.